Abstract

Friday, June 24, 2016

Where Alzheimer's is scarce

Many
claims have been made for turmeric, including its therapeutic prowess to
prevent or limit the ravages of Alzheimer’s. Research by the ethnobotanist
James Duke suggests that extracts of turmeric include natural agents capable of
thwarting the formation of beta-amyloid, a substance that over time hinders cognition and leads to
Alzheimer’s.

In his book The End of
Memory: A Natural History of Aging and Alzheimer’s, Jay Ingram notes that
more than 50 studies link curcumin, turmeric’s active chemical, to lower rates of
Alzheimer’s in India than in most other countries. “In the lab, curcumin both
discourages amyloid beta from aggregating and begins the process of disassembling
already-formed amyloid beta fibrils,” Ingram writes. “Stepping up to the more
complex arena of cell culture, curcumin performs well and is versatile,
reversing or slowing several different chemical processes that contribute to
Alzheimer’s…. [M]ice engineered to be susceptible to Alzheimer’s were put on a
relatively low curcumin diet and after six months had fewer plaques and smaller
loads of plaque-building material.”

But in a starkly counterintuitive finding, using higher
doses of curcumin provided no protection from Alzheimer’s at all. It is
well-known, according to Ingram, that lowering the levels of plaque doesn’t
always enhance cognition. On the other hand, rats injected with amyloid plaque that
were later fed curcumin performed better on water-maze navigation tests. The
curcumin evidently counteracted the damage wrought by the amyloid plaque.

This is an encouraging approach, but a good deal of testing
awaits curcumin’s efficacy. Ingram’s book, which was published about eighteen
months ago, cites a curcumin-related article in Ayu, a journal of Hindu traditional medicine. But the study had an
obvious weakness: only three people participated. A clinical trial in Hong
Kong, which included thirty-four people, did supply some useful data on such
things as absence of side effects. But the placebo group in the study showed no
palpable cognitive decline, drawing the conclusion that “it was impossible to conclude
anything about the efficacy of curcumin.” Not exactly an encouraging result.

Ingram faults other studies, including one in Singapore with
more than 1,000 participants, including Chinese, Indians and Malaysians in the
age range of 60 to 93. He notes that while the scientists sought to control for
numerous other influences, such as diet, exercising and smoking, the group
might have included many undetected factors.

One particularly relevant study compared rates of Alzheimer’s
in Ballabgarh, a rural district near Delhi in India, and the Monongahela Valley
in western Pennsylvania. (Coincidentally, B. Smith, the former celebrity model,
restaurateur and television personality who was diagnosed with early-onset Alzheimer’s
in 2014, grew up in this area of Pennsylvania.) The difference in Alzheimer’s
rates among the two regions is stark. According to Ingram, the rate in Ballabgarh
among people older than 65 is just one percent. In the Monongahela Valley, the
number appears to be about six times that rate. Tellingly, in the local
language in Ballabgarh, there is no equivalent term for “dementia.”

One possible reason is that, much like in North America in
the 1930s, elders in Ballabgarh are likely to live among extended families, and
declining memory capabilities, it seems, are regarded as a common feature of
getting older. One telling figure is that three-fourths of the people in the
study were illiterate. Yet, a crucial feature, according to Ingram, is that far
fewer people in Ballabgarh have the APOE4 gene, a marker for Alzheimer’s.

In a rather deflating conclusion, Ingram writes, “Obviously, when it comes to
curcumin, the evidence that it actually plays a significant role is pretty
scant.” But that’s no reason to stop—or in my case, to start—to consume
turmeric on a regular basis. I happen to like Indian food quite a lot,
especially the dishes with lentils or other legumes. And I plan to purchase a
bottle of the pill version of turmeric soon after I finish writing this piece.

2 comments:

Turmeric is also supposed to be good for arthritis. My results, though, were not so great. I'll try almost anything that will at least do no harm. It's a little hard to know with these things if you are dosing appropriately. I'm just really appreciating this exploration by you, Mitch. My mom and aunt had senile dementia so I'm definitely open to exploring prevention for myself. Thanks!

Turmeric is also supposed to be good for arthritis. My results, though, were not so great. I'll try almost anything that will at least do no harm. It's a little hard to know with these things if you are dosing appropriately. I'm just really appreciating this exploration by you, Mitch. My mom and aunt had senile dementia so I'm definitely open to exploring prevention for myself. Thanks!